The present invention relates to swarf crushers and similar structures in which material to be crushed is supplied to the crusher, typically through a supply hopper supported thereon. It is convenient to operate such crushers for a selected time period which is sufficient to process a load of material but at the same time limits operation to avoid operating the crusher after a load of material has been processed.
As can be expected, during operation of such an apparatus, certain abnormal conditions can which require interruption of the operating cycle. One such typical condition is a stoppage of the crusher because, for example, the crusher is jammed by material even though the motor remains energized. Typically, existing structures are designed to overcome such stoppages by temporarily reversing the crusher and then recommencing operation with the expectation that the cause of the stoppage or the jam will be removed by this cycling. Unfortunately, this is not always the case and in existing structures the cycling continues until the crusher is manually shut down which can result in unnecessary wear and tear of component parts and the control circuit.
In addition, the operating time period continues to run during such abnormal conditions and therefor, in effect, the operating period is shortened by an amount equivalent to the periods of interruption due to the abnormal conditions.